Mathematische Annalen

, Volume 355, Issue 4, pp 1383–1423

\(C^*\)-algebras of Toeplitz type associated with algebraic number fields

  • Joachim Cuntz
  • Christopher Deninger
  • Marcelo Laca
Article

DOI: 10.1007/s00208-012-0826-9

Cite this article as:
Cuntz, J., Deninger, C. & Laca, M. Math. Ann. (2013) 355: 1383. doi:10.1007/s00208-012-0826-9

Abstract

We associate with the ring \(R\) of algebraic integers in a number field a C*-algebra \({\mathfrak T }[R]\). It is an extension of the ring C*-algebra \({\mathfrak A }[R]\) studied previously by the first named author in collaboration with X. Li. In contrast to \({\mathfrak A }[R]\), it is functorial under homomorphisms of rings. It can also be defined using the left regular representation of the \(ax+b\)-semigroup \(R\rtimes R^\times \) on \(\ell ^2 (R\rtimes R^\times )\). The algebra \({\mathfrak T }[R]\) carries a natural one-parameter automorphism group \((\sigma _t)_{t\in {\mathbb R }}\). We determine its KMS-structure. The technical difficulties that we encounter are due to the presence of the class group in the case where \(R\) is not a principal ideal domain. In that case, for a fixed large inverse temperature, the simplex of KMS-states splits over the class group. The “partition functions” are partial Dedekind \(\zeta \)-functions. We prove a result characterizing the asymptotic behavior of quotients of such partial \(\zeta \)-functions, which we then use to show uniqueness of the \(\beta \)-KMS state for each inverse temperature \(\beta \in (1,2]\).

Mathematics Subject Classification (2000)

Primary 22D2546L8911R0411M55

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Joachim Cuntz
    • 1
  • Christopher Deninger
    • 1
  • Marcelo Laca
    • 2
  1. 1.Mathematisches InstitutMünsterGermany
  2. 2.Mathematics and StatisticsUniversity of VictoriaVictoriaCanada